The central objective of this research is to define ways in which drugs interfere with cholinergic systems on subcellular, cellular and system levels, using gas chromagraphy/mass spectrometry in conjunction with both stable and radioactive isotopic labelling to obtain a dynamic assessment of cholinergic processes and the factors controlling them. The dynamics of high affinity choline transport and acetylation, and choline acetylcholine storage and release, will be studied in vitro in synaptosomes, guinea pig myenteric plexus and rat striatal slices, and in vivo in rats. Substrate availability and the effects of precursor loading will be major areas of investigation. These methods will be used to define the effects of drugs on cholinergic systems, the anatomical and biochemical pathways mediating these effects and their relation to the behavioral and pharmacological actions of the drugs. Compounds to be studied include cholinergic and anticholinergic agents and agents such as choline, lecithin and physostigmine which are used to promote central cholinergic activity; hemicholinium, an inhibitor of high affinity choline transport; botulinum toxin and opiates which inhibit acetylcholine release, antidepressants (amitriptyline, DMI), neuroleptics (spiroperidol, chlorpromazine, clozapine) and lithium.